Berlin 2012 – wissenschaftliches Programm
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BP: Fachverband Biologische Physik
BP 5: Statistical Physics of Biological Systems II (with DY)
BP 5.10: Vortrag
Montag, 26. März 2012, 17:15–17:30, H 1058
Molecular Force Response Characteristics from Power Spectral Analysis of Optical Tweezer Experiments — •Yann von Hansen1,2, Alexander Mehlich1, Benjamin Pelz1, Michael Hinczewski1,3, Matthias Rief1, and Roland R. Netz1,2 — 1Physik Department, TU München — 2Fachbereich Physik, FU Berlin — 3IPST, University of Maryland, USA
The thermal fluctuations of micron-sized beads in dual trap optical tweezer experiments contain a wealth of dynamic information about the viscoelastic properties of the experimental object of study. Dynamic deconvolution theory relates the beads’ power spectral densities (PSDs) and the mechanic force response of individual components in the mechanic network [1]. For the quantitative evaluation of the measured signals, a detailed understanding of instrumental characteristics and an accurate calibration of the setup are required. For a simple model system, a pair of unconnected, but hydrodynamically interacting spheres, we obtain excellent agreement between theoretical and measured self- and cross-PSDs over a wide range of inter-bead distances and frequencies, for motion parallel and perpendicular to the inter-bead axis. A comparison to theoretical predictions based on instantaneous hydrodynamics emphasizes the importance of hydrodynamic retardation effects. The viscoelastic response of the force-transducing element between the beads in more complex experimental constructs can be obtained applying a maximum likelihood method [2].
M. Hinczewski et al., Proc. Natl. Acad. Sci. USA 107, 21493 (2010)
Y. von Hansen et al., manuscript in preparation